Re: can I poke the Color Killer with a stick?

[Linards Ticmanis <ticmanis@gmx.de>]

On 04/04/2011 12:04 AM, Osgeld wrote:
> I am diddling around with a program that I want to switch from HGR to
> text and back and everything is fine but sometimes the color killer
> does not switch for sometimes seconds, to sometimes minutes
> (especially in 80 col) is there some magic trick that I can do to get
> this response time down?

If your Computer is a IIe or higher I don't know. If it is a II or II+
and has a Rev. 7 or earlier board, you might have a condition known as
"color carrier leak-through", which is caused by the fact that some TVs
pick up a color carrier even if only tiny amounts of that frequency are
in the signal. The early Apples don't take enough trouble to avoid those
tiny amounts of the carrier frequency in the output.

The fix, eventually added by Apple themselves, consists of one extra
chip (a 74LS02) connected to the "rework area" of your Apple mainboard
(board position A14), a few wires running to it from other chips, and
one cut trace. Check the schematic "Figure 8.7" in Jim Sather's superb
book "Understanding the Apple II" which can be found on the net in PDF
format. The change marked "Rev 8? Rev 9?" at the upper right corner of
that schematic is the change you should make.

-- 
Linards Ticmanis